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Search Results 0 to 2 of about 3 (some duplicates have been removed)
Feb 12, 2013 6:00pm PST
in the air. i mean, the air is around us, right? okay? it leaves behind a hole in the air. aha, but wait a minute, the scholars said, "you can't have a hole in the air, because nature abhors a vacuum." so that vacuum gonna be filled up by the air. so you're gonna squeeze down in back and squeeze it right along. and so there's the force. the air squeezes it along. saturday night when you're taking your bath, try ivory soap, the kind that floats. and you sit in the bathtub and there is a soap right there and you go to grab it. you've done it before and you go, "oh, i have it" it keeps going away from you, right? [laughter] you squeeze it right through the water. well, it was thought that cannonballs were squeezed similarly through the air and arrows too. what do you guys think about that? not too many people were satisfied with that, but that's the best they could do at the time. there gotta be some explanation. what's a better one? and along came an italian type by the name of galileo who turned it all upside down. everyone's looking for the force responsible for the motion, galileo said,
Feb 19, 2013 8:00am PST
inertia and i use a capital "i". and if i put proper units in, i can call it an exact equation. so how much rotational acceleration you're gonna get something to pick up, huh? will depend upon how much torque you put on it, but how much rotational inertia does that something have. it turns out that rotational inertia is complicated. and we're just gonna get the idea of it today. rotational inertia is mr2, the mass multiplied by the distance from the rotational axis when the mass is localized. ordinarily, for different shapes, it's a more complicated equation and we won't get into that, but i can kinda show you that with this idea. here i've got a couple of plastic pipes and in these pipes, i've got some lead. and i'll tell you, the same amount of lead in each one. could i have a helper, please? my helper today gang, this is tinnie lim. she is the lady in that energy chapter who is pulling the bow and arrow back. tinnie was my student at city college in san francisco in 1980. got into conceptual physics, it spurred her on. today, she is a design engineer at jet propulsion labs in califo
Search Results 0 to 2 of about 3 (some duplicates have been removed)